Home Page

Advantages	Disadvantages
-cost is cheap to run damn	-cost is expensive to build damn
-renewable and doesn't pollute	-may haved to be transported through long power lines
-very efficient (up to 90% of gravitational energy can be transformed into electricity	-requires waterfall and fast flowing water
	-silt build up
	-affects ecology of nearby stream or river
	-possible mercury poisoning

Potential Uses
Since hydroelectricity has been around for so long, it is hard to foresee any major breakthroughs in hydroelectric power. However, changes in areas that are unrelated to hydroelectric power, such as computers, and equipment design can effect the future of hydroelectricity. Also, since construction of hydroelectric dams takes a lot of time and energy consumption, major new dams are not expected to be built. However, existing dams are planned to be refurbished and would run at higher efficiency and produce more electricity.

Much remaining hydroelectric potential in the world exists in the developing countries of Africa and Asia. North America and Europe have already had a large percent of hydroelectric power potential developed. Small scale and low head hydroelectric capacity will probably increase in the future as research on low head turbines, and standardized turbine production lowers the cost of hydroelectric power at sites with low heads.

Mechanism by Which Energy is Harnessed
Hydroelectric power is harnessed through the use of a hydroelectric dam. The dam holds back the water gathering up potential gravitational energy. When needed, the water gate on the upper side of the dam is opened, allowing water to rush through, converting its potential gravitational energy into kinetic mechanical energy. The water rushes through a turbine, which is connected to a generator that transforms 90% of the water's energy into electrical energy. The rest of the energy is transformed into useless forms of energy such as sound and thermal. The electricity is then carried through cables to wherever it is needed.

History of Hydroelectric Power
Hydroelectric power has been around for a very long time. Antipater, the Greek poet, mentioned the use of falling water to create energy in 4th century BC writings. The Romans used the wooden waterwheel, but later saw no need to use it, and it wasn't used until centuries later. Then, after war and famine diminished great numbers of Europe's population, laborsaving mills came back into higher use.

On September 30th, 1882, in Appleton, Wisconsin, falling water produced electricity for the first time on the Fox River. The first of many hydroelectric power plants was completed shortly after at Niagara Falls. Hydroelectric power continued to play a major role in the expansion of electrical service early in this century, both in North America and all around the world. However, since that time, the hydroelectric technology has changed quite a bit. Old wooden water wheels have been modified and changed into more efficient turbines. Since these contributions to modern science, hydroelectric power production has risen to an astonishing 2044 billion kilowatt hours worldwide.

Bibliography
Bailey, Mark W. Electricity. Milwaukee: Raintree Publishers, 1988.

Baird, Stuart. Energy Facts: Hydroelectric Power. http://www.iclei.org/efacts/hydroele.htm

Collinson, Alan. Facing the Future Renewable Energy. London: Evans Brothers, 1991.

Deudney, Daniel. "Hydroelectric Power." Grolier '96.

Hydoelectricity: A Viable Renewable Resource. http://starfire.ne.uiuc.edu/~ne201/1996/kao/proj.html

Landis, Fred. "Waterpower." Encarta '98, Microsoft, 1998.

Parker, Steve. Eyewitness Science Electricity. London: Dorling Kindersley, 1992.

Renewable Energy - How Hydropower Works.
http://www.ucsusa.org/energy/hydro.html

Rickard, Graham. Water Energy. England: Wayland Publishers, 1990.

Water Use: Hydroelectric Power.
http://wwwga.usgs.gov/edu/wuhy.html